The present invention relates to the packaging of skeins shaped as circular rings of flexible elements, of elongated shape, such as hoses, cables and the like, and in particular it pertains to a method for packaging the skeins and a packaging machine that implements said method.
The packaging of elongated, flexible, elements into skeins shaped as circular rings currently comprises: a) winding the flexible element onto itself in such a way as to form an ordered succession of turns in mutual contact; and b) connecting the turns together in such a way as to maintain them tightly wound to each other in order to allow the entire skein to be handled as a single body, with no danger that the skein may unravel as a result of the relative displacement of the turns; said connection being hereafter defined with the generic term of binding, regardless of the way said binding is in fact achieved.
The aforesaid packaging is effected by means of various techniques.
A first known packaging procedure provides for the unitary retaining of the turns by means of a certain number of independent bindings, regularly distributed along the skein. Each of these bindings is effected by means of a retaining ring which: is embodied by a strip positioned on its own plane radial to the skein; envelops the turns intersecting their related planes; concatenates with the totality of the turns; and is so tightened as to compress all turns in mutual contact conferring a substantial overall rigidity to the skein.
The aforesaid bindings are obtained by means of machines comprising a certain number of operating heads, or otherwise machines with a single head provided with a plurality of guiding slots, located at regular intervals around the skeins and each forming a ring for holding the turns by dispensing, clamping and cutting a packaging ribbon, commonly called strap, which unwinds from a related coil.
The operating heads are in a well-determined number by construction, so that the related packaging machine can effect a number of bindings exactly corresponding to the number of operating heads, or even a lesser number through the deactivation of one or more heads suitably chosen to allow the formation of bindings regularly distributed along the contour of the skein.
The number and location of the heads with which the machine is provided by construction rigidly condition the operating capabilities of the machine itself Although in general the possibility of varying the binding pitch is not precluded, the aforesaid packaging machines can in fact produce bindings that are mutually offset according to a rather limited number of different pitches so that such machines are characterized, in actuality, by a high productive rigidity.
A second packaging technique, also known and representing an advance over the previous one, calls for combining with the aforesaid bindings, effected with a strap, a band of plastic film (for instance of heat-shrinking material) which is positioned around the circumference of the skein in such a way as to form an exterior sheath, constituted by a single annular strip that encompasses the cylindrical contour surface of the skein and holds the totality of the turns within it. Such containment sheath serves the fundamental purpose of preventing the skein from unraveling while in use when, after the holding rings lying on the radial planes of the skein have been cut or untied, a certain length of hose or cable is extracted and cut from the skein itself.
This packaging technique obviously retains unaltered all the limitations, in terms of binding pitch options, of the machines that embody the technology discussed above. Moreover, it requires a greater manufacturing complexity of the packaging machines; and lastly it entails a greater quantity of packaging material, with obvious consequences both in terms of production cost and of the disposal of the skein packing.
A third packaging method, known from the patent document MC 98A000074, describes a technique that calls for each ring shaped skein to be wrapped entirely, and externally, from one side and from the other, with successive wraps of an uninterrupted, extensible ribbon. The wraps are effected in such a way as to form a sheath wherein each wrap is located on a plane transverse to the skein itself and angularly offset with respect to the wraps that immediately precede and immediately follow.
This packaging method presents numerous advantages, such as that of allowing packaging with very thin film, hence with considerable material savings, and that of allowing to draw and cut the cable from the skein, from the beginning to the end thereof, without it ever being possible for the skein to unravel.
The aim of the present invention is to eliminate all the drawbacks of the known solutions, ascribable to the execution of bindings with predetermined pitch by means of a packaging method able to allow holding the turns of the skein together with bindings distanced at regular pitches with respect to the axis of symmetry of the skein, of any amplitude; able to be modulated progressively and selectable on each occasion according to the specific packaging in process and in particular to the dimensions of the various skeins and to the characteristics of the hose or of the cable that constitute them.
In accordance with the invention, this aim is attained by a machine for packaging skeins of flexible elements, of elongated shape, in particular cables or hoses, shaped as a circular ring and constituted by an ordered succession of turns, said machine being provided with at least a station for binding the turns, and comprising a feeding station provided with skeins clamping means, wherein such clamping means comprise jaws shaped as circular sectors, which are able to rotate around an axis of rotation passing in proximity to its own vertex; said jaws holding the skeins by means of clamping operated on opposite planar faces of the skein and in correspondence with at least a first portion of said faces; a second portion of said faces being let free from clamping and projecting from jaws towards the binding station; said binding station effecting at least one binding of the turns in correspondence with at least the second portion of the skein and effecting such bindings in appropriate phase relationship with the rotations imparted to the skein by the jaws in the feeding station.
The machine has a general configuration that is suited to allow indifferently to realize all binding types with the sole condition of being equipped with the specific type of head corresponding to the different packaging techniques. If the binding station is of the type able to dispense a packing ribbon or a strap, the machine according to the invention allows to realize radial bindings with no constraint limiting the number and distance between the bindings.
If, vice versa, the binding station is embodied by a wrapping head able to dispense a ribbon of plastic film, able to be deformed elastically and longitudinally and uninterrupted, the packaging machine can be set up to provide one of the possible concrete embodiments of the method as per patent application MC 98A000074.